Background and Objectives: The aim of the study was to evaluate the feasibi
lity of retinal thermal damage assessment in a rabbit eye model by using la
ser-induced release of liposome-encapsulated dye.
Study Design/Materials and Methods: After anesthesia, thermosensitive lipos
omes (DiStearoyl Phosphatidyl Choline: DSPC) loaded with 5,6-carboxyfluores
cein were injected intravenously to pigmented rabbits. Retinal photocoagula
tions were performed with a 810nm diode laser (P=100-400 mW, empty set = 50
0 mu m, 1s) (OcuLight(R), IRIS Medical Instruments, Mountain View, CA). Flu
orescence measurements in the area of the laser exposures were then realize
d with a digitized angiograph (CF-60UVi(R), Canon-Europe, The Netherlands;
OcuLab(R), Life Science Resources,(R) UK).
Results: Fluorescent spots were observed for power ranging from 100 +/- 5 m
W to 400 +/- 5 mW. The fluorescence intensity increased linearly with the p
ower and reached a plateau at 280 +/- 5 mW. The fluorescence intensity was
correlated to the maximum temperature at the center of the laser spot with
a linear increase from 42 +/- 3 degrees C to 65 +/- 3 degrees C. These resu
lts are in agreement with our two previous studies with DSPC liposomes for
temperature measurements in a tissue model and then in a vascular model.
Conclusion: This preliminary study demonstrates the possibility of a laser-
induced release of liposome-encapsulated dye for a quantification of diode
laser induced thermal damage in ophthalmology. Such a method could be usefu
l for a real-time monitoring of laser photocoagulation for conditions such
as choroidal neovascular membranes when a precise thermal damage is require
d near the foveolar area. Lasers Surg. Med. 24:61-68, 1999. (C) 1999 Wiley-
Liss, Inc.